Design and simulation of capacitance detection for magnetic mass detection sensor

In the novel prototype of magnetic mass detection structure, the new configured capacitance sensing scheme for the mass detection is analyzed and the circuit detection scheme is implemented. The lock-in amplifier is employed in the capacitance detection to restrain the noise interference. The capacitance analysis using Pspice and Ansys APDL indicates the sensitivity of the detection along 5-DOF (degree of freedom) direction. Capacitance bridge and charge integral amplifier are used as the front signal input interface. The sensitivity of the capacitance detection circuit is 3.4V/pF. When the levitation height is 1mm, the sensitivity of rotation angle is 11.42mv/rad and sensitivity of radial movement is 21mV/mm from the simulation results. The experiment results validate the simulation results. The application of the lock-in amplifier in the field of mass detection sensor is a new attempt, and it shows the prospective for a high-performance application.